Yongwoon Kim
Full-stack Engineer + AI/LLM Specialist
I turn complex business problems into production-grade full-stack and AI systems.
15+ years shipping production-grade full-stack and AI systems across 11 companies — from LegalTech and HR platforms to real-time streaming, e-commerce, and embedded software. Currently leading architecture and delivery for RAG-powered products with OpenAI, LangChain, Next.js, Go, and Python, deployed on AWS · GCP · Azure.
Tech Stack
Featured Projects
A closer look at the work I'm most proud of — from idea to production.
ywc-agent-toolkit
An agent workflow toolkit for Claude Code and Codex
30+ ywc-* skills and dedicated agents that carry ideas through spec, task breakdown, implementation, review, PR, and merge.
30+ ywc-* skills and dedicated agents
Claude Code and Codex command syntax
Idea → Spec → Task → Implementation → Review → PR → Merge
Career History
BizLink, Inc.
2025.06 ~ 2026.03
SES engineer handling contract development for multiple companies. RPA system design/development and GCP infrastructure construction (Terraform). Illegal upload detection system backend design and GCP multi-cloud infrastructure construction (Terraform, Kubernetes). Distributed system development using Python + Flask, Go + Echo, Protocol Buffers, gRPC.
LegalOn Technologies, Inc.
2020.02 ~
Developed AI/NLP annotation platforms and contract management systems. Frontend: Vue.js, Nuxt.js, React, Next.js, TypeScript, Tailwind CSS. Backend: Golang + Gin framework, Ruby + Ruby on Rails, Hanami framework. Infrastructure: Kubernetes, Docker, AWS, GCP, Azure multi-cloud. Led 22+ enterprise projects from architecture design to deployment.
Luum, Inc.
2023.09 ~ 2025.01
Developed AI-powered resume generation platform. Frontend: React. Backend: Golang + Gin framework, Ruby + Ruby on Rails. AI/ML: OpenAI GPT, LangChain RAG systems. Infrastructure: AWS, Kubernetes, Docker. Comprehensive HR platform that automatically generates career documents from LinkedIn profiles and matches with job listings. Designed and implemented LangChain-based AI pipeline.
Drecom Co.,Ltd.
2019.09 ~ 2020.01
Developed community and promotion platforms for user acquisition and retention in gaming and web services. Frontend: React. Backend: Ruby + Ruby on Rails. Database: MongoDB. Infrastructure: AWS. Built real-time user interaction systems and serverless functions.
Emerada Co., Ltd.
2019.03 ~ 2019.08
Developed B2B cash flow management and financial analysis platform. Frontend: React, TypeScript. Backend: Ruby + Ruby on Rails. Database: PostgreSQL. Infrastructure: AWS. Implemented real-time dashboards and financial analysis tools.
Every, Inc.
2018.10 ~ 2019.02
Developed video-based e-commerce platform. Backend: Golang + Echo framework. Provided innovative shopping experience integrating real-time streaming with product sales. Built high-performance backend API and real-time data processing systems.
GREE, Inc.
2017.09 ~ 2018.09
Developed lifestyle platform providing restaurant, travel, hotel, and tourism information. Backend: Ruby + Ruby on Rails, PHP + Laravel. Database: MySQL. Infrastructure: AWS. Built high-traffic handling system and designed scalable architecture. Developed user review and recommendation systems.
DWANGO Co., Ltd.
2016.01 ~ 2017.09
Developed animation and music streaming platforms 'dwango.jp' and 'animelo mix'. Frontend: Backbone.js SPA. Backend: Ruby + Padrino, Java + Spring. Database: MySQL, Oracle. Infrastructure: AWS. Built large-scale content management and streaming platform systems.
Zappallas,Inc.
2013.12 ~ 2015.12
Developed smartphone games targeting female audiences. Built social game platform with JavaScript + PHP + MySQL. Implemented user interaction and social features.
ANDAMUL, INC.
2011.05 ~ 2013.12
Developed novel games for major platforms including Gree, Mobage, MIXI, and Hangame. Frontend: JavaScript, jQuery, CSS. Backend: PHP. Database: MySQL. Game engine development and multi-platform API integration.
DigitalCraft, Inc.
2010.07 ~ 2011.05
Developed embedded systems and STM32 microcontroller modules based on TOPPERS RTOS. Development Environment: Linux, Cygwin. Language: C++. Implemented real-time OS and hardware control software. Designed and optimized TECS component architecture.
Let's build something together
Looking for help on a specific engineering challenge? I take on consulting, contract, and full-time engagements. Here are a few ways I can help:
System architecture & API design for full-stack and AI products
Production-grade AI/LLM systems — RAG pipelines, agent workflows, and integrations
Tech leadership & end-to-end delivery across backend, frontend, and infra
Multi-cloud engineering on AWS, GCP, and Azure (Kubernetes, Terraform)
Drop me a message below, and I'll get back to you within 2 business days.